Electrophonic stringed instrument



Patented Apr. 27, 1937 ELECTROPHONIC, STRINGED INSTRUMENT Arthur J. Stimson, in Angelou, Colin, minor, by mesne assignments, to Rudolph Dopyera,

Los Angeles, Calif.

Application January 19,.

6 Claim.

This invention relates to improvements in stringed musical instruments.

The. general object of the invention is to provide a stringed musical instrument including improved means for directing the vibrations of the strings to an electrical amplifier.

Another object of the invention is to provide a novel electrical pick-up for stringed musical instruments.

An additional object of my invention is to provide a novel mounting for the electrical pick-= up of a musical instrument.

A further object of the invention is to piovide a novel tail-piece for anchoring the tail ends of the strings of a musical instrument.

Other objects and the advantages of the inven-- tion will be apparent from the following description taken in connection with the accompanying drawing wherein:

Fig. l is a top plan view of a guitar embodying the features of my invention;

Fig. 2 is an enlarged fragmentary view similar to Fig. 1 with the cover partly broken away;

Fig. 3 is a section taken on line 3-3 of Fig. 2:

181g. 4 is a section taken on line 3-4 of Fig. 2; an

Fig. 5 is a wiring diagram showing the manner in which I electrically connect the guitar and an electrical amplifier.

Referring to the drawing by reference char= acters, I have shown my invention as embodied in a guitar indicated generally at iii. The guitar ill includes a body l2 of the usual shape having thereon the usual neck IS on which the usual guitar strings it are provided. The body it in= cludes a top 15, a bottom it and sides it. The top it has a circular aperture ill therein and positioned in the aperture I provide a cylindrical wall member IS. The top of the wall it] is spaced slightly below the upper surface of the top i and it extends downward to the bottom iii where it is held between a dish l9 and an annular ring l9".

This provides a chamber in which I ar range an anchor member which I have indicated generally at 2|. The anchor member it is preferably made of aluminum and includes a body portion 22 having adjacent one end a trans= verse upstanding flange 23 thereon (see Fig. 4). L Opening through the upper surface oi the flange 23, I provide a slot 24 in which a metal bridge member 25 is positioned.

On the face of the flange 23 opposite the body portion 22 the flange includes boss 23 in which a plurality of vertical slits 21 are provided. The

1934, SerialNo. 101,300

(El. 84 l.)

lower ends of the slits open into an arcuate recess 23 in the under face of the boss. Integral with the body 22 and the flange 23 I provide a pair of angularly extending arms 23. Adjacent the end of the anchor body 22 opposite the flange 23 I provide a small upstanding flange and intermediate the flanges 23 and Y30 I provide an angularly disposed upstanding flange 3! of less height than the flange 23.

Positioned on the body 22 between the flanges 3t and 3i 1 provide a horse-shoe-magnet 32. Positioned on the flange 3i and on the magnet 32 adjacent the pole ends thereof I provide electromagnets 3t and it of the spool type each of which includes a that, rather elongated, core member 35 which extends above and below the windings. hers 35 each engage one of the pole ends of the magnet 32. The upper faces of the core members 35' are preferably inclined towards each other as indicated at 36.

The magnet 32 is shown as secured in position by a rod 31 (see Fig. 4) having a bent end portion 38 which is positioned in a recess 39 pro vided in the outer face of the curved portion of the magnet 32. The end of the rod 31 opposite the portion 38 is threaded and extends through an aperture 40 in the flange 3i and has a nut 41] thereon. When the nut ii is tightened the rod 3i draws the magnet 32 towards the flange 3i and tightly clamps the core members 35 oi the magnets 33 and it between the pole ends of the magnet it and the flange iii.

The ends-oi the arms 29 of the anchor member are positioned on the upper face .of the wall 99 and are secured thereto by screws 42. The end oi the body 22 opposite the arms 23 is supported on a member which is suitably secured to the dish it. The body is secured to the member it by a screw (it.

The ends of the strings Ml include the usual enlarged members which are positioned in the recess 2t oi the boss 28 and the strings are positioned in the slots Bl thereof and pass over the bridge member 25. When the strings it are drawn tight they engage the upper surface of the bridge member '25 and are spaced above the upper surfaces oi the core members 35 of the electromagnets W and 34. By sloping the upper faces oi the core members as previously described and indicated at 33 the distance from the core members to the strings may be varied to suit the requirements. Also positioning the core members at an angle to the strings enables further tone variations to be secured.

The lower portions of the core mem- Positioned over the chamber 20, I provide a cover member 45' which includes a string aperture l8 and an aperture 41 through which the core members 35 project.

Mounted on the side of the body 22 of the anchor member 2i I provide a step-up autotransformer 48 of any standard type and supported on the cover 45' I provide a resistance I unit 49 which includes an operating knob 50 positioned above the cover. The resistance unit 49 may be of any standard type including a resistance coil ii and a slider 52 diagrammatically shown in Fig. 5.

As further shown in Fig. one end of the coil 5 of the electromagnet 33 is connected by a wire 53 to one end of the coil of the other electromagnet 34. The opposite end of the coil 33 is connected by a'wire 54 to one end of the resistance coil ii and the opposite end of the electromagnet coil 34. is connected by a wire 55 to an amplifying unit 56. The slider 52 of the resistance unit 49 is connected by a wire 51 to the coil 38 of the transformer intermediate the length thereof. The opposite end of the resistance coil BI is connected by a wire 63 to the wire 55.

One end of the transformer coil is connected by a wire 30 to the wire 55 and the opposite end of the transformer coil is connected by a wire 6| to the amplifying unit 56. The'ampllfying unit 56 is shown as connected by wires 62 and 63 to an electrically actuated resonator 64.,

In the use of my invention the movement of the strings il-which constitute para-magnetic bodies over the cores of the magnet produces a change in the magnetic permeability of the core and thereby induces various voltages which are ill: synchronization with the vibrating member From the foregoing it will be apparent that I I 40 have provided novel means for directing the vibrations of the strings of ai stringed musical instrument through an electrically actuated res- L onator which is simple in construction and highly eflicient in use.

Having thus described my invention, I claim: 1. In a pick-up for a stringed musical instrument which includes an anchor member, a string supporting bridge and means to secure one end of the strings to said anchor member, a horse- 50 shoe magnet adapted to be securedto said anchor member and a pair of eiectro-magnets each including a coil and an elongated core member 65 be positioned diagonally relative to the strings with the strings passing over said core members and spaced closely adjacent, and thereabove, the upper faces of said core members being inclined downward towards eachother.

aovasso 3. In a pick-up unit for a stringed instrument, an anchor member, a horse-shoe magnet mounted on the anchor member and adapted to be positioned below the strings of a musical instrument, a pair of electro-magnets including core members extending above and below their associated windings, said core members each engaging one pole of said horse-shoe magnet, said core members being adapted to be positioned transversely of the strings and to be spaced closely adjacent and below the strings with faces of said core members adjacent the strings inclined away from said strings towards the adjacent faces of said core members, said electro-magnet windings being adapted to be connected to a resonator unit.

4. In a pick-up unit, an anchor member adapted to be mounted on the body of a stringed musical instrument, said anchor member including a stringed supporting bridge and means to engage one end of the strings of the musical instrument, a horse-shoe magnet on said anchor member, and a pair of electro-magnets each including a spool member and an elongated core member extending above and below the spool member, said core members each engaging one pole of said horse-shoe magnet, said core members being adapted to be positioned diagonally relative to the strings with the strings passing over said core members and being spaced closely adjacent and thereabove, the upper faces of said cores being inclined downward towards each other.

5. In a pick-up unit, an anchor member adapted to be mounted on the body of a stringed musical instrument, said anchor member including a stringed supporting bridge and means to engage one end of the strings of the musical instrument, a horse-shoe magnet on said anchor member, a pair of electro-magnets each including a spool member and an elongated core member extending above and below the spool, said core members each engaging one pole of said horse-shoe magnet, the upper faces of said core members being inclined, said core member being adapted to be spaced closely adjacent and below the instrument strings and the windings of said electro-magnets being adapted to be connected. to an electrically actuated resonator.

6. In a pick-up unit, an anchor member adapted to be mounted on the body of a stringed musical instrument, said anchor member including a stringed supporting bridge and means to engage one end of the strings of the musical instrument, a horse-shoe magnet on said anchor member, a pair of electro-magnets each including a spool member and an elongated core member extending beyond its associated spool, said core members each engaging one pole of said horse-shoe magnet, said core members beingadapted to be positioned diagonally across the strings with the upper faces of said cores inclined downward towards each other, and with the core members spaced closely adjacent and below the strings, said electro-magnets being adapted to be connected to an electrically actuated resonator.

ARTHUR STIMSON. 

